The SEARCH for Diabetes in Youth Study documented a 31% increase in the prevalence of type 2 diabetes (T2D) between 2001 and 2009, as well as an increase of 21 % in the prevalence of type 1 diabetes (T1D) in youth diagnosed at age<20. Increases occurred across most but not all major subgroups of age, sex and race/ethnicity. Further, we documented an annual increase in the incidence of T1D among non-Hispanic white youth of approximately 2.7% per year. In contrast, studies from Europe suggest that incidence of T1D may be stabilizing. Ongoing, efficient surveillance of diabetes diagnosed in youth is essential to inform health care systems and generate testable hypotheses related to the natural history of diabetes in youth. SEARCH is uniquely positioned to address these critical questions through continued surveillance of childhood diabetes employing our well-established infrastructure for surveillance, and our highly experienced, collaborative and multi-disciplinary investigative team. Therefore, in response to RFA-DP-15-002, Component B, we propose the continuation of the SEARCH for Diabetes in Youth Registry Study (SEARCH Phase 4) during which we will continue to serve as the Coordinating Center (CC). Our approach is informed by our substantial accrued experience that allows us to provide statistical and operational leadership in a highly efficient manner. The overarching aim of the CC is to support the population based registries of Component A described in the RFA, specifically the activities of the surveillance network and the validation of diabetes cases. The main objectives of the registries are to ascertain, among youth diagnosed at age < 20 years, cases of prevalent diabetes in calendar year 2017; ascertain newly diagnosed (2015-2020) incident diabetes cases; confirm classification of diabetes type using biochemical markers; and optimize efficiency of the surveillance activities through targeted projects designed to utilize relevant electronic health data. The main objectives of the CC to support the surveillance network are to: (1) Maintain a central data repository and create protocols and mechanisms to secure transmission of data and relevant data management reports between the CC and the registry sites; (2) Ensure the training and certification of staff on measurements and procedures as outlined in the protocol and manual of operations; (3) Provide expertise and leadership in population-based surveillance development, methodology, implementation, and evaluation; (4) Provide statistical and other analytic support to the registry network; (5) Provide for a central laboratory for the analysis of biological specimens; (6) Provide operational support to the registry network (communication and meetings). The main objectives of the CC to support the validation of diabetes cases are to: (1) Develop analytic methods for case validation; (2) Provide statistical/analytic support for validation analysis; (3) Maintain diabetes case validation protocols. Thus, the CC is uniquely positioned to provide leadership in statistical and operational issues that will support continued collection of data on the prevalence, incidence and early clinical course of diabetes in youth.